JPS6149513A - Ultrasonic delay line - Google Patents

Abstract

PURPOSE:To prolong an ultrasonic wave propagation path and to increase element fitting areas by forming slanting surfaces by cutting two corner parts of a rectangular glass delay medium, and fitting piezoelectric converting transducing elements to the wide surface and using the narrow slanting surface as an ultrasonic wave reflecting surface. CONSTITUTION:The two corner parts of the rectangular delay medium 1 are cut to form two different-area slanting surfaces, and the piezoelectric transducing elements 2 and 3 are fitted to the wide-area slanting surface. In this constitution, when an electric signal is applied between electrodes of the input-side element 2, the element 2 oscillates mechanically corresponding to the frequency of the signal to radiate an ultrasonic wave into the medium 1. The ultrasonic wave propagates in the medium 1 as shown by a solid line to reach the output-side element 3 at the output side, and consequently the element 3 oscillates mechanically to generate an electric signal between electrodes corresponding to the frequency. Thus, the ultrasonic propagation path is prolonged and the element fitting area is increased, so unnecessary reflection is reduced by using large piezoelectric elements and band characteristics and loss characteristics are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic delay line used to improve the image quality of video equipment such as VTRs, TVs, video discs, and video cameras.

Conventional configuration and its problems FIG. 1 shows the structure of a conventional glass retardation medium.

Piezoelectric transducer elements 2 and 3 provided with electrodes and having an electro-mechanical energy conversion function are attached to the slope of the glass retardation medium 1. When an electric signal is applied between the electrodes of the piezoelectric transducer 2 on the input side, the piezoelectric transducer 2 mechanically vibrates according to the frequency of the signal and emits ultrasonic waves into the glass delay medium 1. This ultrasonic wave propagates through the glass delay medium 1 along the path indicated by the solid line and reaches the piezoelectric transducer 3 on the output side at the other end, causing the piezoelectric transducer 3 to mechanically vibrate in accordance with its frequency. An electrical signal E0 is generated between the electrodes. At this time, if the sound speed of the delay medium is V and the length is l, the time t required for the ultrasonic wave to reach the output end from the input end is expressed as t = l/v, and the output signal is equal to the input signal This means that there is a delay of t. This t is called the delay time. FIG. 2 shows a front view of the conventional system. In order to obtain t as long as possible in as small an area as possible, it is necessary to increase the dimensions 81 and a2 in the figure, which are &1-a2 here. These al and a2 become larger, and as a result, the dimensions for mounting the piezoelectric transducer 2.3 become smaller, and smaller piezoelectric transducers 2 and 3 must be used.
The beam angle becomes wider and the unnecessary reflection level increases. It also has the disadvantages of smaller capacity, larger insertion loss, and narrower bandwidth.

OBJECTS OF THE INVENTION In view of the above-mentioned drawbacks, the present invention aims to provide an ultrasonic delay line which reduces unnecessary reflections and has insertion loss and band characteristics equal to or greater than those of the conventional ultrasonic delay line.

Structure of the Invention In order to achieve the above object, the ultrasonic delay line of the present invention has a glass delay medium in which two corners of a rectangle are cut out, and the two slopes formed by the cutout have different areas. A piezoelectric transducer is attached to the larger area of the two slopes,
The narrower slope is at least one of the ultrasonic reflecting surfaces, and by adopting this structure, the ultrasonic propagation path can be made longer, and the area on which the piezoelectric transducer is mounted can also be increased.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

The configuration of the ultrasonic delay line is substantially the same as that explained in FIG. 1, so the explanation will be made using the same squares.

FIG. 3 is a front view of the ultrasonic delay line of the present invention, in which 1 is a glass retardation medium with two corners of a rectangle cut out, and two slopes formed by cutting out the glass retardation medium 1. The areas are different from each other, and the piezoelectric transducers 2 and 3 are attached to the one with the larger area.

With this configuration, when an electrical signal is applied between the electrodes of the piezoelectric transducer 2 on the input side, the piezoelectric transducer 2 mechanically moves according to the frequency of the signal, and transmits ultrasonic waves into the glass delay medium 1. discharge. This ultrasonic wave propagates through the glass delay medium 1 along the path shown by the solid line, and passes through the piezoelectric transducer 3 on the output side at the other end.
This causes the piezoelectric transducer 3 to mechanically vibrate and generate an electrical signal between the electrodes according to the frequency.

As described above, in the present invention, the dimensions of al and a2 shown in FIG. 2 are not the same, and as shown in FIG. a
3 is shortened, so the slope dimension is as small as a dog.
Piezoelectric transducers 2 and 3 that are equal to or greater than conventional piezoelectric transducers can be attached to the slope. Therefore, it was possible to obtain an ultrasonic delay line with small unnecessary reflections and excellent band, loss, and arrow characteristics.

FIG. 4 shows unnecessary reflections, and FIG. 5 shows frequency characteristics for the conventional example shown in FIG. 2 and the case shown in FIG. 3 which is an embodiment of the present invention. This shows that the present invention is superior in terms of unnecessary reflection, band, and loss.

Effects of the Invention As described above, the ultrasonic delay line of the present invention has two corners of a rectangular glass delay medium cut out so as to have different areas, and the piezoelectric transducer element is attached to the wider side. The propagation path of the piezoelectric transducer remains the same and the delay time can be set for a predetermined time, and the area where the piezoelectric transducer is mounted can be increased, allowing the use of a large piezoelectric transducer, which reduces unnecessary reflections and improves band characteristics and loss characteristics. It can be made into an excellent product and is a dog of industrial value.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventional ultrasonic delay line, Fig. 2 is a front view of the same, Fig. 3 is a front view showing an embodiment of the ultrasonic delay line of the present invention, and Fig. 4 is a perspective view of the conventional ultrasonic delay line. FIG. 5, which is a comparison diagram of unnecessary reflection levels of the ultrasonic delay line of the invention, is also a frequency characteristic comparison diagram. 1... Glass delay medium, 2, 3... Piezoelectric conversion element. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (1)

[Claims] The areas of the two slopes formed by cutting out the two corners of a rectangle are different from each other, and the piezoelectric transducer is attached to the larger area of the two slopes, and the piezoelectric transducer is attached to the narrower one. An ultrasonic delay line whose slope is at least one of the ultrasonic reflecting surfaces.